A wide range of equipment has been proposed to assist in the draining of fluid from wounds, particularly wounds resulting from surgery or accidents. One type of known construction employs a bellows type container that can be reduced in volume against the pressure of internal springs or by the force of deformation of the container material to provide a vacuum source.
These types of construction exhibit several major limitations one being that to achieve the desired level of vacuum, the container must have a high degree of resilience to develop a vacuum of the order of several pounds per square inch. This is somewhat impractical in terms of cost effective manufacture and it is not possible to effectively control or maintain the desired vacuum level for efficient drainage. Further, as only a small degree of vacuum can be created, it dissipates rapidly as the container fills with fluid. Also, it is normally very difficult, if not impossible, to monitor accurately the rate at which the fluid is collected.
Another known type of equipment for the extraction and collection of wound fluid employs a disposable container connected to a re-useable electronically driven pump, and thus require elaborate and expensive electronics, a pump and rechargeable batteries or a power supply. The inherent complexities of this type of device entails significant additional cost for initial purchase and for maintenance of the pump and controller. While the fluid containers are disposable, special provisions must be made to ensure that the non-disposable components, such as the pump assembly, are protected from contamination by the drained wound fluid.
Yet a further known type of wound fluid collector is that employing a pre-evacuated container which use volatile liquids such as pentane and hexane to achieve the required level of vacuum. However these do not provide a capability to vary or otherwise control the level of vacuum, and if a leak occurs which dissipates the vacuum there is no ability to re-establish the vacuum. These systems often operate at a higher degree of vacuum than is ideally desired for optimum drainage in many situations.
There is a variant of this latter form of wound fluid collector which use an elaborate, separate, non-adjustable regulator of the flexible throttled tube type which can be attached to the drain bottle. This does help to avoid an overly strong suction, but still has the other shortcomings of the non-regulated system and additionally there is the substantial added cost of the regulator, which cannot be re-used for another patient, as the regulator becomes contaminated by the drained wound fluids during use.
The present applicant has previously proposed a flow control valve to, in use, selectively provide communication between the conduit and container, said valve means being adopted to establish communication between the conduit and the container in response to the existence of a level of vacuum in said conduit below a selected value. Such a device has been proposed in the present applicant's prior international patent application PCT/AU95/00674 (published as WO 96/11031) and granted in the United States of America as U.S. Pat. No. 5,944,703 and in Europe as EP 0783339, the contents of both of which are incorporated herein in their entirety. Embodiments of the device disclosed therein incorporate a compliant element, attached to a regulator valve, which compliant element is induced to flex by rotation against a circular ramp. The degree of flex induced is related to the degree of rotation, and can be read against a calibrated scale. The upward force resulting from the flexion of the compliant member moves the regulator valve, breaking the seal of the valve seat and allowing fluid to be drawn through a spigot tube into a drain container, thereby lowering the pressure in the area below the regulator valve, and through the orifice, equally lowering the pressure in the connecting tube and the drain tube. The magnitude of force applied by the compliant element is selectively adjustable by a rotational movement of the compliant element. The higher the force applied by the compliant element, the higher the level of vacuum maintained in the tube. Whilst such a device has been found to be efficacious in improving flow control, it has been found that under some circumstances the valve may be accidentally or unintentionally incorrectly adjusted, thereby causing an incorrect under or over setting of vacuum control between the wound drainage conduit and the container.
Improper setting can result in either insufficient drainage from the wound due to low vacuum, resulting in build up of fluid in the wound and increasing risk of infection, or, if incorrectly set to a high vacuum, causing discomfort to the patient. It has been realised that in such a device as disclosed in U.S. Pat. No. 5,944,703 and EP 0783339, the incorrect adjustment or setting may occur due to a patient or other person accidentally, unintentionally or absentmindedly rotating the compliant member. Also, another person, such as a carer or medical staff, may accidentally or un-intentionally rotate the compliant member when attending to personal needs of the patient, such as when adjusting the patient's clothing/bedding.
With the aforementioned in mind, it is desirable of the present invention to provide an improved apparatus for controlling closed wound drainage especially in regard to a avoiding incorrect flow control setting.